Friday, July 10, 2015
A Lychrel number is an integer (any length) that does NOT eventually form a palindromic number (reading the same backwards & forwards) after following a process of reversing its digits and adding, reversing and adding, etc....
for example, starting with 837:
837 1575 7326 13563 50094
738 5751 6237 36531 49005
1575 7326 13563 50094 99099 <== palindromic
Simple enough, and in most cases a palindrome is arrived at within fairly short order.
BUT in the case of 196 no such palindrome has ever been reached. There is no proof that one does not exist somewhere waaaaay out there, though it seems unlikely; but why? why 196? There are actually several additional numbers thus far not found to produce palindromes, 196 is just the smallest of them. In fact, NO Lychrel numbers have ever been proven to exist in base 10, just plenty of candidates.
More from MathWorld: